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9.9 Option – Space science: 4.
Parts of space ships must withstand launch and re-entry
| Syllabus reference (October 2002 version) | ||
|---|---|---|
| 4. The components and materials
used in the construction of rockets and shuttles must withstand launch
and re-entry conditions |
Students learn to:
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Students: |
Extract from Senior Science Stage 6
Syllabus (Amended October 2002) © Board of Studies, NSW.
[Edit: 9 June 09]
Background: Before the space industry could begin, scientists and engineers had to develop and test materials to see if they could withstand conditions of lift-off and re-entry. Heating due to friction was the main problem to be overcome so heat resistant material had to be developed. Also fuel had to be able to give the space vehicle enough force to overcome the force of gravity on lift-off and in the case of the shuttle put them into orbit.
gather and process secondary information to trace changes in the type of systems that have been used in space travel and discuss the advantages and disadvantages of using a shuttle
- Use books in the library, including encyclopaedias and use the internet
to gather information about
early systems and how they have changed
NASA.
Click on any one of the space vehicles for more detail.
Another website is First Generation Soviet Space Systems Encyclopedia Astronautica, National Geographic.
- Process the information from the various sources by assessing the information from the sources for reliability. Which source would you expect to be more accurate if there are discrepancies?
- You could make your notes for the space shuttle under two headings, Advantages and Disadvantages.
describe the functions of the components of the Space Transport System (STS), commonly called shuttle, including:
- the orbiter
- solid rocket boosters (SRB)
- external tank
- The winged orbiter carries both crew and cargo. The orbiter differs from previous spacecraft in that it glides to a runway landing in the manner of an ordinary jet aeroplane. The orbiter is designed to reduce the high cost of space flights, and it can be reused as many as 100 times.
- A pair of large, solid-propellant, booster rockets are used and they are jettisoned about two minutes after lift-off when they have used up their fuel. They are then parachuted to Earth for retrieval and eventual reuse.
- The external tank contains liquid hydrogen (fuel) and liquid oxygen (oxidizer) for the orbiter's three main rocket engines. After the orbiter has used up the propellants in the external tank, the shuttle has virtually reached maximum velocity and the external tanks are released to burn up in the atmosphere and two manoeuvring engines give the Shuttle the final push into orbit.
identify some of the difficulties experienced during lift-off but not on re-entry into the Earth’s atmosphere
- During lift-off spacecraft have to overcome the force of gravity.
- A lot of fuel must be carried to enable the spacecraft to escape from the Earth’s gravitational field.
- This fuel increases its weight so more force is required to lift the extra weight.
- When the space shuttle returns, it lands at an angle aided by wings like a jet plane does. The atmosphere is used as a retarding force resulting from aerodynamic drag.
- On re-entry the shuttle no longer has the excess weight as it has ejected the booster fuel rockets and used up the fuel from the external tank, which has been jettisoned into space to burn up.
- The shuttle glides in to land with a very low demand on fuel, just a very long runway.
explain why a large booster rocket is required during lift-off but not on re-entry
- During lift-off spacecraft have to overcome the force of gravity.
- The shuttle takes off vertically so it travels directly against the force of gravity.
- A lot of fuel must be carried to enable the spacecraft to escape from the Earth’s gravitational field.
- This fuel increases its weight so more force is required to lift the extra weight.
- The booster rocket is needed to carry the extra fuel.
- When the space shuttle returns, it lands at an angle aided by wings like a jet plane does. The atmosphere is used as a retarding force resulting from aerodynamic drag.
- On re-entry the shuttle no longer has the excess weight as it has ejected the booster fuel rockets and used up the fuel from the external tank, which has been jettisoned into space to burn up.
- The shuttle glides in to land with a very low demand on fuel, just a very long runway.
describe properties of materials used in the STS and relate the properties to conditions experienced during lift-off or re-entry
- To protect the orbiter from the high temperatures experienced during re-entry, the craft is covered with a variety of silica glass fibre tiles. These tiles are about 0.25mm thick and are made of 94% air by volume.
- Some of the tiles were replaced by Fibrous Insulation Blankets. One blanket could replace 25 tiles. The blanket consists of layered pure silica felt sandwiched between a layer of silica fabric and a layer of silica glass fabric. The blanket is bonded directly to the vehicle structure and then coated with a high purity silica coating to improve erosion resistance.
- To protect the orbiter from great pressure reinforced carbon carbon (RCC), an all carbon composite material is used. As this also has good thermal properties it is placed behind the tiles and blankets. The RCC is only used a points of great pressure such as behind the nose cap and on the wing leading edges.
- The lowest temperatures during re-entry of 370 degrees Celsius (700 degrees Fahrenheit) are met by the upper fuselage, which is fitted with coated Nomex felt. The thermal protection system is reusable except for a few tile changes after each flight.
- During a 90 minute orbit the external temperature goes from –128 degrees Celsius (–200 degrees F) to 93 degrees Celsius (+200 degrees F) so both cold and hot temperatures need to be withstood but these are very minor compared to the temperatures of re-entry
- NASA has produced a
fact sheet with this information if you want more detail.
gather, process and present information from secondary sources on plans for future space vehicles
- There will always be new space missions planned but
it is unlikely this will be available in books so you will have to use the
internet To gather information on planned space vehicles go to Space
Futures.com . These vehicles are planned for commercial travel.Although the text describes vehicles today most of them are still in the experimental stage.
- NASA plans future space travel to include:
- Space adventure tourism and travel
- Space business parks
- Clean, solar electric power beamed from space to Earth's population
- Space hospitals for treatment of chronic pain and disabilities
- Asteroid mining of high-value minerals
- Worldwide, two-hour express package delivery
- To find out information on the European
Space Agencies new technologies.
- If you want to research a third space agency decide which one to research. The Chinese and Indians have space programs. Go to a search engine and type in the words you need according to what you are researching.
- Compare the vehicles from the different agencies. Are they doing quite different things or is there a lot of overlap? Are the functions of the future vehicles quite different? Do you think they consult with each other? What is the evidence for your decision?
- Present your information to the class. Use diagrams, photographs or videos if they are available. Use a table if it makes the information clearer.
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